#include <bits/stdc++.h> using namespace std; #define F first #define S second #define MP make_pair #define PB push_back #define all(x) begin(x), end(x) using ll = long long; using pi = pair<int, int>; using pll = pair<ll, ll>; using str = string; template<typename T> using vec = vector<T>; template<typename T, size_t N> using arr = array<T, N>; const ll INF = 1e17; const int MOD = 1e9 + 7; int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); int N; cin >> N; vec<int> d(N + 1), x(N + 1); vec<ll> dp(N + 1); for (int i = 1; i <= N; i++) cin >> d[i] >> x[i]; dp[1] = 1; dp[2] = -1; ll ans = 0, sum = 0; for (int i = 1; i <= N; i++) { sum = (sum + dp[i]) % MOD; ans = (ans + sum) % MOD; if (i < N) dp[i + 1] = (dp[i + 1] + sum) % MOD; if (i + x[i] + 1 <= N) dp[i + x[i] + 1] = (dp[i + x[i] + 1] - sum + MOD) % MOD; } cout << ans << '\n'; }